Lord Llewellyn, who was formerly David Cameron’s chief of staff in Downing Street, told MPs that while his staff are making contact with other French presidential candidates they have no relations with the Front National leader.

He told the Foreign Affairs select committee: “With respect to the Front National, we have a policy of not engaging, there is a longstanding policy. That is the policy, which has been the policy for many years.”

Mr Llewellyn said that any change in the Government's policy would be a "matter for ministers". It comes after accusations that Britain failed to build links with Donald Trump because he was considered an outsider for the presidency.

Ms Le Pen is widely expected to make the final round runoff in May against one of the other leading candidates, most likely either François Fillon, a centre-right Republican, or Emmanuel Macron, an independent.

Lord Llewellyn had earlier confirmed that his team in Paris had spoken to the teams of other candidates.

He said: “We know who the candidate is on the centre-right, the candidate is Monsieur Fillon, obviously we have contacts with him and his team.

“On the left we don’t know who the candidate is going to be. We will know the answer on 29 January after the second round of primaries … my team [is] in touch with people across the picture on the left.”

Ms Le Pen has led efforts to detoxify her far-right party and now focuses on anti-immigration policies and her desire for France to quit the Euro.